fix(mesh): filtered decode must not depend on the requested subset

models_named pruned to the wanted set BEFORE distinct assignment, so collision
resolution saw a different resource population and returned different offsets:
27 of 356 resources in Stage_S02 decoded differently when asked for alone,
including real geometry (f001_bdy_30, f106_sld_02_l/m/d, f101_wep_01_l). Both the
viewer and assemble_ship decode subsets, so both could disagree with the
container's own answer. This was a regression from distinct assignment itself.

Fixed by filtering the OUTPUT: the assignment always runs over the whole
container. One-name, three-name and full decodes now agree exactly. Cost: a
single-resource query on a 50MB container goes from near-instant to ~15s;
per-container caching is the follow-up. Ten suites green.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/sylpheed-formats/src/mesh.rs

@@ -523,11 +523,13 @@ impl Xbg7Model {
             }
             let name = read_cstr(bytes, e.name_offset as usize + DIR_BASE)
                 .unwrap_or_else(|| "XBG7".to_string());
-            if let Some(w) = wanted {
-                if !w.contains(&name) {
-                    continue;
-                }
-            }
+            // NOTE: `wanted` is NOT applied here. Distinct assignment resolves
+            // collisions against the whole set of resources, so pruning first
+            // made a filtered decode depend on *which* subset was asked for —
+            // measured 2026-08-12: 27 of 356 resources in `Stage_S02` came out
+            // at a different offset when requested alone. The filter is applied
+            // to the OUTPUT instead, so a subset is always a subset of the
+            // container's own answer.
             resources.push(Res {
                 name,
                 markers,
@@ -722,6 +724,9 @@ impl Xbg7Model {
             }
             models.push(m);
         }
+        if let Some(w) = wanted {
+            models.retain(|m| w.contains(&m.name));
+        }
         out = models;
         out
     }